Angle of incidence

[S2D]

Can anyone tell me what the angle of incidence is for the T craft.

[Len Petterson]

Re: Angle of incidence

The front spar shall be 1 and 5/16" higher when the rear spar at the first full rip from the tip. Measured at the bottom of the spars.
With the tail surface level. Use a 30" long level or longer.
I suggest you make a small wood block to the correct dimension and tape it to the level. Makes it easyer.
Len

[S2D]

Re: Angle of incidence

Thanks Len, I found that on the new SB, but I was just curious what the actual number was for the AOI for that airfoil on the Tcraft.

[flyguy]

Re: Angle of incidence

If you are seeking an angle number in degrees it is pretty easy to figure. Little trigonometry problem. Ask Hank here, he is our Resident Engineer. JK Hank.
Just measure between spars. With the 1-5/16 number, whip out your trusty calculator and bingo you have an angle.

But you are correct, likely someone here knows the number.
Darryl

[Forrest Barber]

Re: Angle of incidence

3 degrees 49 minutes from memory about 25 years ago???

[Hank Jarrett]

Re: Angle of incidence

Kool, I was just getting up to go get my slide rule.
Hank

Calculator? give me my trusty slip stick!

That's my Pickett by my left sleeve.

[S2D]

Re: Angle of incidence

Thanks Forrest. that may be the number I'm looking for.

Incidently, I don't believe the 1 5/16" number has anything to do with the angle of incidence, it is just a handy way to see if the wing has the proper amount of washout.

[N96337]

Re: Angle of incidence

I've always wondered what kind of resluts you'd get from flattening it out.... sure did wonders for the SC!
JH

[flyguy]

Re: Angle of incidence

That is what I was thinking about the washout myself.
For sure too much lift at higher cruise with 85 HP or more. I pretty much run out of trim at higher power settings and you just know that you're dragging the fuselage through the air "sideways" (vertical.) Elevator trimmed out of streamline doesn't help any either. And mine is kinda slow because of a few things like big tires and a flat prop.
DC

[Forrest Barber]

Re: Angle of incidence

I do not want to get real technical, all this is on the forumn somewhere, we did all this testing at the factory. You wizz kid engineers can take take the 23012 Airfoil and show others the effective chord line. the angle this makes with the relative wind when the horizonial stab is level is what we arei talking about ( at the fuselage attach point.)
Then we found of course this had to be changed with higher HP engines and increased cruise; so we raised the leading edge of the stabs either 3/4 or 1 inch on the Clipped Taylorcrafts. This effectively lowered the AOI , get your slide rules out and figure it out. Go to the NACA study of Airfoils and you will find a lot; HOWEVER way back then I could never find data on the inverted condition; we did our own.
The 23012 has a higher stall speed inverted than upright. about 54 MPH vs the 44MPH normal of the Leisa Marie with 29 ft wing and 1280 Gross. Kind of neat, I used to roll inverted and climb out in front of the crowd doing a climbing 180 degree left turn and if I pushed too much she could stall , roll and recover at the lower airspeed. ( safely too!) . I have film of the tests including the inverted spin tests..

[TimHicks]

Re: Angle of incidence

Wow!
I'd like to see that film someday.

[N95334]

Re: Angle of incidence

I've always wondered what kind of resluts you'd get from flattening it out.... sure did wonders for the SC!
JH

Now I am confused "flattening it out" do you mean no washout?
Does the BC-12 D have washout? How much, does this 1 5/16 inch mean at the tip it should be 1 5/16th and at the root near fuselage zero?

"Wonders for the SC" what is SC?

[N96337]

Re: Angle of incidence

Dennis,
I was refering to "flattening out" the angle of incidence, not washout. Don't mess with washout...you need that wing to stall at the root first.
Angle of incidence is the relative angle between the wing chord line and longitudinal axis of the airplane. (see Forrest's post above, also) They found some pretty big variences in Super Cubs when they were doing the "0 Thrustline" mods, and it seemed the ones that had less angle were showing more results from the thrustline mods. (I'm shooting that from memory...so it could be the opposite...you can do a search on 0 thrustline and spend a while reading..it's really very interesting)
As Forrest said, with the higher horsepowers, they raised the leading edge of the horizontal stab, thus effectively reducing the angle of incidence in a sense. The same function is basically performed by the jackscrew on a moveable stabilizer, which I think would be a great mod for a Tcraft! I think if you'd do away with the trim tab, and go to a moveable stab, the Tcraft would be an even better performer than it already is.
JH

[S2D]

Re: Angle of incidence

Dennis,
I was refering to "flattening out" the angle of incidence, not washout. Don't mess with washout...you need that wing to stall at the root first.
Angle of incidence is the relative angle between the wing chord line and longitudinal axis of the airplane. (see Forrest's post above, also) They found some pretty big variences in Super Cubs when they were doing the "0 Thrustline" mods, and it seemed the ones that had less angle were showing more results from the thrustline mods. (I'm shooting that from memory...so it could be the opposite...you can do a search on 0 thrustline and spend a while reading..it's really very interesting)
As Forrest said, with the higher horsepowers, they raised the leading edge of the horizontal stab, thus effectively reducing the angle of incidence in a sense. The same function is basically performed by the jackscrew on a moveable stabilizer, which I think would be a great mod for a Tcraft! I think if you'd do away with the trim tab, and go to a moveable stab, the Tcraft would be an even better performer than it already is.
JH

Yea, its the opposite. 1.8* measured on the bottom of the spars worked better than the .9*. (thats the Min and Max tolerance for the front and rear spar attach fitting in the fuselage).

[N96337]

Re: Angle of incidence

Thanks Brian.... That sounded right at the start...then when I typed it, it looked wrong......haha
JH